J-ethyl-z



United States Patent O Y 3,125,448 PHOTOGRAPHIC SILVER HALIDE EMULSIONSCONTAINING CATIONIC MEROCYANINE DYES Donald W. Heseltne and Lewis L.Lincoln, Rochester,

N.Y., assignors to Eastman Kodak Company, Rochester, N.Y., a'corporation of New Jersey Filed Mar. 10, 1960, Ser. No. 14,101 9Claims. (Cl. 96-105) This invention relates to a novel class of dyes,and more particularly to cationic merocyanine dyes useful as bleachableantihalation and lter dyes-,- and as optical sensitizers in photographicsilver halide elements.

It is known that photographic elements require, for many purposes, lightscreening substancesl incorporated therein. Such a light screeningsubstance may be in a layer overlying a light sensitive emulsion oroverlying two or more light sensitive emulsions; or it may be in a lightsensitive emulsion for the purpose of modifying a light record of suchan emulsion or protecting an overlying light sensitive emulsion oremulsions from the action of light of wavelength absorbed by such lightscreening substance; or it may be in a layer not containing a lightsensitive substance but arranged between two light sensitive emulsions;or it may be in a layer serving as a backing on an element having one ormore light sensitive emulsions (for example, to reduce halation).

In a particular, light screening substances are often required (a) inovercoatings upon photographic elements to protect the light sensitiveemulsion or emulsions from the action of light which it is not desiredto record, e.g., ultraviolet light in the case of still or movingpictures, especially color pictures, (b) in layers arranged betweendierentially color sensitized emulsions eg., to protect red and greensensitized emulsions from the action of blue light, and (c) in backings,forming the so-called antihalation layers, on either side of atransparent support carrying the light sensitive emulsion or emulsions.

Numerous substances have been employed as light screening materials forthe purposes indicated above. Many of these, however, are not resistantto diiusion and wander from the layer in which it is intended that theyshould remain. Some of them are not as water soluble as is desired andtherefore present problems in their incorporation in the filter layers.Some dyes are not readily bleachable or destroyed in the photographicprocessing and present stain problems in the processed photographicelement.

It is therefore an object of the invention to provide a novel class ofdyes which are valuable for use in making light sensitive photographicelements.

Another object is to provide a novel class of cationic merocyanine dyesfor making light absorbing filter layers and antihalation layers inphotographic elements which not only have valuable light absorbingcharacteristics but are more water soluble than prior art merocyaninedyes and are thus more easily incorporated in the filter layer.

Another object is to provide a novel class of dyes which are useful asphotographic sensitizers.

Another object is to provide a novel class of cationic merocyanine dyesfor light absorbing filter layers which not only have the desired lightabsorbing properties and solubility properties but which are furthercharacterized by being less subject to diiusion from the filter layerthan are the prior art dyes.

Another object is to provide a novel class of dyes which not only havethe above desired characteristics but also are bleachable by thedeveloper solution during the processing of the photographic element.

Another object is to provide a photographic element having at least onesensitive silver halide emulsion layer and alight absorbing filter layercontaining a dye selected from the novel class of dyes of our invention.

Still another object is to provide a photographic element having atleast one sensitive silver halide emulsion layer containing asensitizing amount of a dye selected from the novel class of dyes of ourinvention.

Still other objects will become apparent froml the followingspecification.

We have discovered that the above objects can be accomplished by the useof the novel dyes of our invention. Our dyes have a characteristicstructure which distinguishes them from the prior art dyes. Thisstructure has a methine chain with one terminalcarbon atom substitutedwith a pyridinium group and with a phenacyl group, a cyano group or abenzothiazolyl group, and the other terminal carbon atom forms a part ofa; heterocyclic nucleus such as a benzothiazole nucleus, a benzoxazolenucleus or a 4-quinoline nucleus.

The novel dyes of our invention can advantageously be expressed by theformula:

wherein R is a lower alkyl group havingv from 1 to 6 carbon atoms suchas methyl, ethyl, propyl, butyl, isobutyl, amyl, isoamyl, hexyl,-methoxy ethyl, -ethoxy ethyl, allyl (i.e. vinylmethyl), benzyl(phenylmethyl), -phenylethyl, carboxymet'hyl, etc.; Z represents thenonmetallic atoms necessary to complete a heterocyclie nucleus,containing from 5 to 6 atoms in the heterocyclic ring, such as thoseselected from thev group consisting of those of the thiazole series (cg'., thiazole, 4-methylthiazole, 4-phenylthiazole, S-methylthiazole,5phenylthiazole, 4,5-dimethylthiazole, 4,5-diphenylthiazole,4-(2-thienyl)thiazole, etc.), those of the benzothiazole series (e.g.,

benzothiazole,

4-chlorobenzothiazole, 5-ch1orobenzothiazole, -chlorobenzothiazole,7-chlorobenzothiazole, 4-methylbenzothiazole, S-methylbenzothiazole,-methylbenzothiazole, 5-broinobenzothiazole, -brornobenzothiazole,4-phenylbenzothiazole, S-phenylbenzothiazole, 4-methoxybenzothiazole,S-methoxybenzothiazole, 6-metl1oxybenzothiazole, S-iodobenzothiazole,6-iodobenzothiazole, 4-ethoxybenzothiazole, 5-ethoxybenzothiazole,tetrahydrobenzothiazole, 5,6-dimethoxybenzothiazole,5,6-dioxymethylenebenzothiazole, 5hydroxybenzothiazole,6-hydroXybenzothiiazole, etc.),

those of the naphthothiazole series (e.g., naphtho[ 1,2] thiazole,

naphtho [2,1 thiazole, 5-methoxynaphtho [2, 1 thiazole,

5 -ethoxynaphtho [2,1 thiazole, 8-methoxynaphtho[ 1,2] thiazole,

7 -methoxynaphtho 1,2] thiazole, etc.) those of thethanaphtheno-7,6,4',5thiazole series (e.g.,4methoxythianaphtheno7,6,4,S-thiazole, etc. those of the oxazole series(c g. 4-methyloxazole,

S-methyloxazole, 4-phenyloxazole, 4,5-diphenyloxazole, 4-ethyloxazole,4,5-dimethyloxazole, 5phenyloxazole, etc.), those of the benzoxazoleseries (e.g., benzoxazole, 5-chlorobenzoxazole, 5methylbenzoxazole,S-phenylbenzoxazole, -methylbenzoxazole, 5,6-dimethy1benzoxazole,4,6-dimethylbenzoxazole, S-methoxybenzoxazole, 5ethoxybenzoxazole,S-chlorobenzoxazole, -methoxybenzoxazole, 5hydroxybenzoxazole,6-hydroxybenzoxazole, etc.) those of the naphthoxazole series (eg,naphtho 1,2] oxazole, naphtho[2,1]oxazole, etc.) those of the selenazoleseries (eg, 4-methylselenazole, 4-phenylselenazole, etc.) those of thebenzoselenazole series (e.g., benzoselenazole, 5-chlorobenzoselenazole,5methoxybenzoselenazole, 5-hydroxybenzoselenazole,tetrahydrobenzoselenazole, etc.), those of the naphthoselenazole series(eg, naphtho 1,2] selenazole, naphtho[2,1]selenazo1e, etc.) those of thethiazoline series, e.g., thiazoline, 4-methylthiazoline, etc.), those ofthe 2-quinoline series (e.g., quinoline, 3-methylquino1ine,S-methylquinoline, 7methylquinoline, 8-methylquino1ine,6-ch1oroquinoline, 8-chloroquinoline, 6-methoxyquinoline,-ethoxyquinoline, -hydroxyquinoline, S-hydroxyquinoline, etc.) those ofthe benzimidazole series (e.g., 1,3-diethylbenzimidazole,1-ethy1-3-phenylbenzimidazole etc.) those of the 3,3-dialkylindolenineseries (e.g., 3,3-dimethylindolenine, 3,3,5-trimethylindolenine,3,3,7-trimethylindolenine, etc. those of the 2-pyridine series (eg,pyridine, S-methylpyridine, etc.), those of the 4-pyridine series (e.g.,pyridine, etc.), etc.; d is a positive integer of from 1 to 2; n is apositive integer 1, 2, or 3; W is a benzoyl group, a cyano group, or abenzothiazolyl group; Q is a heterocyclic nucleus such as a pyridiniumgroup, a substituted pyridinium group, a quinolinium group, asubstituted quinolinium group and etc.; X is an acid anion such asiodide, chloride, bromide, perchlorate, etc.

The preferred dyes of our invention can be expressed by the formula:

e i02m-N :ort-orpi C1039 l @M 1beuzoy1-3[1-ethyl-4-(1H)quiuolylideue]propenylpyridinium perchlorate 1-`benzoy1-3-[ 3ethy1-2 3H)-benzothiazolylidenel -propenylpyridinium iodide /gwawg I@dienylpyridinium tio DYE 41 6- 3ethy12 3H -benzo thiazolylidene]-2,4hexadienylidene phenacyl pyridinium iodide DYE 52-[3-(3-ethy1-2(3H)benzoxazo1y1idene)1-(1-pyridiuiun1 perchlorate)propeuyl] benzothiazole DYE 6 2-[3-(3-etliyb2 (3H)benz0thiazoly1idene)-1- l-pyridinium perchlorate) propenyl] benzothiazole The merocyaninedyes represented by Formula I above can advantageously be prepared bycondensing a cornpound selected from those represented by the followingformula:

(III) --z N IR-Z- o rrd-o n) lh-(eiken) .FN-nil i i. wherein R, Z, d andn are each as defined above; Y

represents an acid radical such as chloride, bromide,

can be accelerated by basic condensing agents such asy the trialkylamines, (e.g., triethylamine, tri-N-propylamine, triisopropylamine,tri-N-butylamine, etc.), N,N dialkylanilines (e.g., N,Ndimethylaniline,N,N-diethy1 aniline, etc.), N-alkylpiperidines (e.g.,N-methylpiperidine, N-ethylpiperidine, etc.), etc. The condensations areusually carried out in the presence of basic solvents such as pyridine,quinoline, etc., (ie. heterocyclic tertiary amines). The condensationsare accelerated by heat and are normally carried out at the refluxtemperature of the reaction mixture.

Among the preferred salts of Formula IV used for making our dyes arethose having the cation 1phenacyl pyridinium, l-cyanomethylpyridinium,and benzothiazolylmethylpyridinium.

The preparation of salts having a cation with an active methylene groupsuch as are used in making our dyes is illustrated by the preparationsbelow.

1PHENACYLPYRIDINIUM BROMIDE Dry pyridine ('2 mols., 31.6 g.) andvc-bromoacetophenone (1 mol., 39.8 g.,) were mixed and allowed to standat room temperature for fifteen minutes. At this point the reactionmixture turned darker in color With the evolution of heat. The reactionmixture was thenvallowed to stand at room temperature overnight. The

product was thrown out oi solution by adding an excess of ether withstirring, the ether decanted from the residue, and the product obtainedas a solid by refluxing with acetone. The salt was ltered olf, Washedwith acetone and dried. After one recrystallization from ethyl alcoholthe yield of pure quaternary'salt was 44.5 g. M.P. 197-198" C.

l-CYANOMETHYLPYRIDINIUM CHLORIDE Dry pyridine (l mol., 15.8 g.) andchloroacetonitrile (l mol., 115 g.) were mixed and allowed to stand atroom temperature for fteen minutes. At this point the reaction mixtureevolved heat yielding a light tan solid. The solid cake was then heatedon a steam bath for thirty minutes, cooled, ground under acetone,filtered oli and dried. Aften one recrystallilation from ethyl alcoholthe yield of pure quaternary salt was 25 g. (80% M.P. 178-l79 C.decomposition.

I-(Z-BENZOTHIAZOLYLMETHYL) PYRIDINIUM PERCHLORATE Prepared as describedby Walter Ried and Heinz Bender, Chemische Berichte 89, p. 1893-1896(1956).

The preparation of our dyes is further illustrated by the followingexamples.

Examplel I'DYE El.

l-phenacylpyridinium bromide (1 mol., 2.78 g.), 4--acetanilidovinyl-l-ethylquinolinium iodide (l mol., 4.44 g.) andtriethylamine (2 mols., 2.8 ml.) were dissolved in dry pyridine (30 ml.)and heated under reflux for ten minutes. The reaction mixture was thenchilled overnight and the crude dye precipitated from solution as asticky mass by adding an excess of ether with stirring. The ethersolution was decanted, the residue dissolved in Water and the dyeprecipitated as the perchlorate salt by adding sodium perchlorate. Thecrude dye was filtered olf, washed with water and dried. After tworecrystallizations from methyl alcohol, the yield of pure dye Was 1.8 g.(40% M.P. l95 196 C., decomposition.

Example Il DYE 2 l-phenacylpyridinium bromide (1 mol., 2.78 g.), 2-/3-acetani1idovinyl-3-ethylbenzothiazolium iodide (1 mol., 4.5 g.) andtriethylamine (2 mols., 2.8 m1.) were dissolved in dry pyridine (30 ml.)and heated under reflux for ten minutes. The reaction mixture was thenchilled overnight and the crude dye precipitated from solution by addingan excess of ether with stirring. The crude dye was ltered olf, washedwith water and dried. After two recrystallizations from methyl alcohol,the yield of pure dye was 2.2 g. (43%), M.P. 1275-2716" C.,decomposition.

Example III 'DYE 3 l-phenacylpyridiniurn bromide (l mol., 2.78 g.),2-(4- acetanilido 1,3v butadienyl) 3 ethylbenzothiazolium iodide (lmol., 4.76 g.) and triethylamine (2 mols., 2.8 ml.) Were dissolved indry pyridine (30 ml.) and heated under rellux for ten minutes. Thereaction mixture was then chilled overnight and crude dye precipitatedfrom solution by adding an excess of ether with stirring. The crude dyewas filtered oli, washed with water and dried. After tworecrystallizations from methyl alcohol, the yield of p'ure dye was 1.5g. (30%), M.P. Z22223 C., decomposition.

Example 1V myn i 3 ethyl 2 methylbenzothiazolium p toluenesulfonate (1mol., 34.9 g.) and glutaconicaldehyde dianilide hydrochloride (l mol.,28.4 g.) were mixed in acetic anhydride m1.) and refluxed for tenminutes. The

brown solution was chilled and the product precipitated from solution asan oily mass by adding ether (400 ml.) with stirring. The residue wasobtained crystalline by stirring with acetone (100 mi), solid filteredoff, washed with more acetone and dried. The yield of 2-(6-acetanilido1,3,5 hexatrienyl 3 ethylbenzothiazolium) ptoluenesulfonate was 29 g.(53%), MP. 175 176 C.

lphenacylpyridinium bromide (1 mol., 1.39 g.), 2-(6- `acetaniliclo 1,3,5hexatrienyl-3-ethylbenzothiazolium) ptoluene-sulfonate (1 mol., 2.67 g.)and triethylamine (l mol., 7 ml.) were dissolved in dry pyridine andheated under reflux ten minutes. The reaction mixture was then chilledovernight and the crude dye precipitated from solution as a sticky massby adding an excess of ether with stirring. The ether solution wasdecanted and the residue dissolved in water, and the dye precipitated asthe iodide salt by adding sodium iodide. The crude dye was filtered off,lwashed with `water and dried. After two recrystallizations from aqueousmethyl alcohol, the yield of pure dye was 0.8 g. (30%), MP. 161-162 C.

Example V c.DYE 5 DYE" 6 1-(Z-'benzothiazolylmethyDpyridiniumperchlorate (1 mol., 3.27 g.), Z-aCetanilidovinyl-B-ethylbenzothiazoliumiodide (1 mol., 4.5 g.) and triethylamine (1 mol., 1.4 ml.) weredissolved -in dry pyridine (2O ml.) and heated under reflux for twentyminutes. The reaction mixture was then chilled overnight and the crudedye precipitated from solution by .adding an excess of ether withstirring. The crude dye was iiltered off, washed with water and dried.After two recrystallizations from methyl alcohol, the yield of pure dyewas 1.2 g. (24%), M.P. 234235 C., decomposition.

Example VII DYE 7 l-cyanornethylpyridinium chloride (1 mol., 1.55 g.), 2acetanilidovinyl3-ethylbenzothiazolium iodide (l mol., 4.5 g.) andtriethylamine (l mol., 1.4 ml.) were dissolved in dry pyridine andheated under reflux for live minutes. The reaction mixture was thenchilled overnight and the crude `dye filtered olf, washed sparingly withmethyl alcohol and dried. After two recrystallizations from methylalcohol, the yield of pure dye was 1.9 g.

(44%), Mr. 23S-234 C., decomposition.

Example VIII DYE 8 l-cyanomethylpyridinium chloride (l mol., 1.55 g.), 2(4-acetanilido1,3-butadienyl)-S-ethylbenzothiazolium iodide (l mol.,4.76 g.) and triethylarnine (l mol., 1.4 ml.) were dissolved in drypyridine ml.) `and heated under reux `for five minutes. The reactionmixture was then chilled overnight and the crude dye filtered olf,washed with acetone and dried. After -two recrystallizations from methylalcohol, the yield of pure dye was 1.8

g. (40%), NLP. 205-206 C., decomposition.

Example 1X DYE 9 l-cyanomethylpyridinium chloride (l mol., 1.55 g.),4--acetanilidovinyl-l-ethylquinolinium iodide (l mol., 4.4 g.) andtriethylamine (l mol., 1.4 ml.) were dissolved in dry pyridine (30 ml.)and heated under reux for five minutes. The reaction mixture was thenchilled overnight and the crude dye ltered off, washed sparingly withmethyl alcohol and dried. After two recrystalliziations from methylalcohol, the yield of pure dye was 3 g. (70%), M.P. 221-222" C.,decomposition.

Our dyes have light absorbing characteristics that make them valuablefor use in light absorbing and antihalation layers of photographicelements. These characteristics are .illustrated by Table I below.

TABLE I Maximum light absorption by dye occurs at a wavelength in m DyeNumber Our dyes are readily soluble in water because of their ionicnature and are thus readily incorporated in hydrophilic colloids such asgelatin, polyvinyl alcohols, albumin, casein which are usually used forsuch layers. A stock solution may advantageously be made of the dye tobe used and this can simply be added as desired to the hydrophiliccolloid before it is to be coated.

The concentration of the dye used in the hydrophilic colloid may varyconsiderably vdepending upon the product in which the filter layer orthe antihalation layer is to be used. The method of determining theproper amount of dye to tbe used for a given product is well known inthe art.

In the accompanying drawing, FIGURES 1 and 2 are enlarged sectionalviews of photographic elements having iilter layers or antihalationlayers made according to our invention. As shown in FIGURE 1, a support10 of any suitable material such as cellulose acetate, cellulosenitrate, synthetic resin materials or opaque materials such as paper, iscoated with an emulsion layer 11 and an overcoating layer 12 containinga cationic merocyanme dye of our invention.

FIGURE 2 represents a lm having an antihalation layer containing acationic merocyanine dye according to our invention. As shown therein,the support 10 carries an emulsion layer 11 and an antihalation layer 13containing a cationic merocyanine dye on the opposite sides.

The following examples will illustrate more fully how our dyes may beused in preparing light absorbing filter layers.

Example X 1.5 gram of dye No. 1 was dissolved in 371/. ccs. of water andthis solution was added to 4.5 liters of 5% aqueous gelatin. Thismixture was then coated as an antihalation backing on the reverse sideof a support which had been coated with a photographic silver halideemulsion layer.

After exposure of the photographic element in the usual manner,development of the exposed material in a developer having the followingcomposition:

Grams N-methyl-p-arninophenol sulfate 2 Sodium sulfite (desiccated)Hydroquinone 8 Sodium carbonate monohydrate 52.2 Potassium bromide 5Water to make 1 liter.

lresulted in complete removal of the dye from the photographic element.

Example Xl A photographic element made as in Example X was exposed andtreated in a conventional sodium thiosulfate lixing bath. The dye wascompletely bleached by this treatment.

Example XII A photographic element made as in Example X but using dye 4in place of dye l, was exposed. No dye was left in this element afterdevelopment with a developer such as was used in Example X.

ExampleA XIII image.

Example XIV Similarly, the other dyes of our invention can be used inlight filtering layers as in Example No. XIII.

Although the above examples show the use of our dyes in antihalationlayers and in layers overcoating the light sensitive silver halideemulsion layer, they can also be coated between light sensitive silverhalide layers in multilayer photographic elements.

Some of our dyes are useful as sensitizers for optically sensitizingsilver halide (e.g., silver chloride, silver bromide, silver iodide,silver chlorobromide, silver bromoiodide, etc.) emulsion layers inphotographic elements. The following table illustrates the wavelengthsof light to which a silver bromoiodide emulsion layer is sensitized bysome of our dyes.

TABLE II Wavelength, Range of Wavein ma, of light lengths, in ma, DyeNo. to which emulto which emulsion has highsion is sensiest sensitivitytized 565 565-590 600 GOO-630 700 60C-720 490 490-52() 530 B30-575 55055C-615 660 i300-700 640 60G-670 The sensitizing eiect is furtherillustrated by FIGURES 3, 4 and 5 of the attached drawings which showwedge spectrograms for three dyes of our invention.

FIGURE 3 shows the sensitizing effect produced in a silver halideemulsion by our cationic dye l-benzoyl-S- [3-ethyl-2( 3H)-benzothiazolylidene] -l ,S-Pentadienylpyridinium iodide.

FIGURE 4 shows the sensitizing elfect produced in a silver halideemulsion by our cationic dye 1-cyano-3-[3- ethyl -2 (3H)benzothiazolylidenell propenylpyridinium iodide.

FIGURE 5 shows the sensitizing ellect produced in a silver halideemulsion by our cationic dye l-cyano-S-[3- ethyl-Z-(3H)benzothiazolylidene] 1,3-pentadienylpyridinium iodide.

The solubility characteristics of our dyes, as well as the goodbleaching characteristics that they show in photographic developers andother processing solutions combined with the sensitizing characteristicsshown by some of our dyes makes them useful as sensitizers forphotographic elements.

lll

The concentration at which our dyes are used in emulsions as opticalsensitizers may vary considerably depending upon the particularphotographic product in which they are to be used and the electsdesired. The sensitizing amounts of a particular dye needed for aparticular silver halide emulsion is determined by techniques well knownin the art.

The novel cationic merocyanine dyes of our invention are characterizedby being readily water soluble and readily bleachable by ordinaryphotographic developers and processing solutions. These properties makeour dyes valuable for use in making light sensitive photographicelements. Some of our dyes are particularly valuable in light absorbinglter layers either overcoating the -silver halide emulsion layers orcoatings between the light sensitive silver halide layers or coatings onthe support of the photographic element over which the light sensitivesilver halide emulsion layers are coated. Some of our dyes are alsocharacterized by having useful optical sensitizing effects onphotographic silver halide emulsions.

The invention has been described in detail with particular reference topreferred embodiments thereof, but it will be understood that variationsand modifications can be effected within the spirit and scope of theinvention as described hereinabove and as dened in the appended claims.

We claim:

l. A photographic element comprising a support having thereon at leastone sensitive silver halide emulsion layer, at least one layer of saidphotographic element containing a dye having the formula:

wherein R is a lower alkyl group having from l to 6 carbon atoms, Zrepresents the non-metallic atoms needed to complete a heterocyclicnucleus containing from 5 to 6 atoms in the heterocyclic ring, drepresents a positive integer of from l to 2, n represents a positiveinteger of from l to 3, Q represents a member selected from the classconsisting of a pyridinium group and a quinolinium group such that thenitrogen atom in said Q group is attached to the terminal carbon atom inthe conjugated chain, W represents a member selected from the classconsisting of the cyano group, a benzoyl group, and a benzothiazolylgroup, and X represents an acid anion.

2. A photographic element comprising a support having thereon at leastone sensitive silver halide emulsion layer, at least one layer of saidphotographic element containing a dye having the formula:

wherein R is a lower alkyl having from l to 6 carbon atoms, n is apositive integer of from l to 3, W is a member selected from the groupconsisting of a cyano group, benzoyl groups, and benzothiazolyl groups,R1 is a member selected from the class consisting of a hydrogen atom, abromine atom, a methyl group, and a phenyl group, provided that when R1is selected from the class consisting of a methyl group and a bromineatom, said R1 group is substituted on the carbon atom meta to thenitrogen atom of the pyridine ring, and X is an acid anion.

3. A photographic element comprising a support having thereon at leastone sensitive silver halide emulsion layer,

at least one layer of said photographic element containing a dye havingthe formula:

wherein R is a lower alkyl group having from l to 6 carbon atoms, n is apositive integer of from 1 to 3, W is a member selected from the classconsisting of a cyano group, benzoyl groups and benzothiazolyl groups,R1 is a member selected from the class consisting of a hydrogen atom, abromine atom, a methyl group and a phenyl group, provided that when R1is selected from the class consisting of a methyl group and a bromineatom, said R1 group is substituted on the carbon atom meta to thenitrogen atom of the pyridine ring, and X is an acid anion.

4. A photographic element comprising a support having thereon at leastone sensitive silver halide emulsion layer, at least one layer of saidphotographic element containing a dye having the formula:

12 R1 group is substituted on the carbon atom meta to the nitrogen atomof the pyridine ring, and X is an acid anion.

5. A photographic element comprising a support having thereon at leastone sensitive silver halide emulsion layer, at least one layer of saidphotographic element containing the dye 1-cyano-5-[3-ethyl-2-(3H)-benzothiazolylidene]-1,3-pentadienylpyridinium iodide.

6. A photographic element comprising a support having thereon at leastone sensitive silver halide emulsion layer, at least one layer of saidphotographic element containing the dye6-[3ethyl-2(3H)-benzothiazolylidene1-2,4-hexadienylidenephenacylpyridinium iodide.

7. A photographic element comprising a support having thereon at leastone sensitive silver halide emulsion layer, at least one layer of saidphotographic element containing the dyel-benzoyl-3[1-ethy1-4(1H)quinolylidene]- propenylpyridinium perchlorate.

8. A photographic element comprising a support having thereon at leastone sensitive silver halide emulsion layer, at least one layer of saidphotographic element containing the dye1-cyano-3-[3-ethyl-2(3H)benzothiazolyl idene]propenylpyridinium iodide.

9. A photographic element comprising a support having thereon at leastone sensitive silver halide emulsion layer, at least one layer of saidphotographic element containing the dye1benzoy13[3-ethyl-2(3H)-benzothiazolylidene]propenylpyridinium iodide.

References Cited in the file of this patent UNITED STATES PATENTS2,231,659 Brooker et al. Feb. ll, 1941 2,395,879 Kendall et al. Mar, 5,1946 2,471,996 Anish May 31, 1949 2,647,050 Firestine July 28, 19532,704,714 Carroll et al. Mar. 22, 1955 2,870,014 Brooker et al. Jan. 20,1959

1. A PHOTOGRAPHIC ELEMENT COMPRISING A SUPPORT HAVING THEREON AT LEASTONE SENSITIVE SILVER HALIDE EMULSION LAYER, AT LEAST ONE LAYER OF SAIDPHOTOGRAPHIC ELEMENT CONTAINING A DYE HAVING THE FORMULA: